Performance of Brushless Multiphase Synchronous Generator (BMSG)

Brushless and magnetless synchronous machines are gaining popularity due to their numerous advantages in wind energy applications. These machines typically have three phases with dual, special windings or require harmonic excitations to create decoupled fields in airgap for brushless excitation and power/torque production. Multiphase electric machines offer benefits such as fault tolerance and reduced converter switch ratings per phase. Additionally, they can independently control multiple fields with varying numbers of pole pairs (spatial harmonics) using a single winding. This advantage improves torque density, slot fill factor, and derating while wirelessly transferring power to excite the rotor of wound-field synchronous machines. In this paper, a generating mode of operation is proposed to design multiphase electric machine windings. These windings can control the magnitude and angular location of dual pole magnetic fields, each with a different desired number of pole pairs. For instance, a 4/8 pole, 5-phase example is provided, and through controlling these dual poles, excitations and power generation are varied independently. The machine is validated using finite element analysis (FEA).